Question: Solve for $x$ and $y$ using substitution. ${6x-y = 4}$ ${x = 5y-9}$
Explanation: Since $x$ has already been solved for, substitute $5y-9$ for $x$ in the first equation. ${6}{(5y-9)}{- y = 4}$ Simplify and solve for $y$ $30y-54 - y = 4$ $29y-54 = 4$ $29y-54{+54} = 4{+54}$ $29y = 58$ $\dfrac{29y}{{29}} = \dfrac{58}{{29}}$ ${y = 2}$ Now that you know ${y = 2}$ , plug it back into $\thinspace {x = 5y-9}\thinspace$ to find $x$ ${x = 5}{(2)}{ - 9}$ $x = 10 - 9$ ${x = 1}$ You can also plug ${y = 2}$ into $\thinspace {6x-y = 4}\thinspace$ and get the same answer for $x$ : ${6x - }{(2)}{= 4}$ ${x = 1}$